Final answer:
The membrane affected by inflammation on the surface of the stomach is the visceral peritoneum, which covers the abdominal organs.
Step-by-step explanation:
When a patient experiences inflammation of the membrane on the surface of the stomach, the membrane affected is the visceral peritoneum. This is because the visceral peritoneum is the part of the peritoneum that envelopes the abdominal organs, including the stomach. The parietal peritoneum, in contrast, lines the abdominal wall. The peritoneal cavity, filled with a lubricating watery fluid, lies between the parietal and visceral layers, allowing for minimal friction and protecting against inflammation.